A mechanochemistry‐driven practical and efficient synthetic protocol for accessing diverse series of biologically relevant poly‐functionalized 5‐(arylselanyl)‐1H‐1,2,3‐triazoles through copper(I)‐catalyzed click reaction between aryl/heteroaryl acetylenes, diaryl diselenides, benzyl bromides, and sodium azide has been accomplished under high‐speed ball‐milling. Advantages of this method include operational simplicity, avoidance of using solvent and external heating, one‐pot synthesis, short reaction time in minutes, good to excellent yields, broad substrate scope, and gram‐scale applications. Furthermore, synthesized organoselenium compounds were synthetically diversified to biologically promising selenones. [ABSTRACT FROM AUTHOR]